Sunday, July 1, 2018

Your Casita Tongue Weight Is Critical To Safe Travel

NHTSA data shows an estimated 50,000 trailer towing related accidents occur each year. Most of these accidents are a result of preventable side to side trailer sway. Crosswinds, drafts from passing semi-trucks or descending hills using incorrect braking technique can initiate trailer sway. In such cases, the rear of the trailer can act as a pendulum that increasingly swings back and forth. As the trailer makes this swaying movement, it can push the tow vehicle into fish-tailing movements. The intensity of the swaying movements can lead to trailer flipping over, which may, in turn, overturn your towing vehicle.

Uneven weight distribution -- too much weight loaded in the rear of the trailer -- is a significant cause of trailer side to side sway increasing to disaster, once it starts. Packing a few tens of pounds to the rear of the trailer can make profound changes in the rig's sway control stability. But properly balanced trailer weight can naturally dampen and stop trailer sway.

But by following a few simple guidelines, you can stay on track, towing with the utmost ease and safety. Swaying trailers are almost always the result of the center of gravity weight not being far enough foreword from the axle, which commonly referred to as insufficient tongue weight. Increasing tongue weight increases stability, but don't add too much weight to your tow vehicle's hitch.

If there is zero tongue weight, the trailer's center of gravity (CG), the point around which it pitches, yaws and rolls, is centered between the tires' contact patches. This will provide no stability, specifically in yaw, or sway. Adding tongue weight, by moving cargo in the trailer forward, pulls the CG forward of the tire contact patches. The drag of the tires will tend to pull the CG back onto the center line of the truck and trailer. The more tongue weight, the farther forward the CG goes, and the more stability in sway, right up until you add too much tongue weight for the tow vehicle's rear suspension to handle. Your trailer tongue weight must be at least 10 to 12 percent of total (gross) trailer weight for safe sway-free towing.
Remember, your trailer axle is a fulcrum, or “seesaw” pivot point. The center of gravity weight is shifted fore and aft of the axle -- on to and off of the trailer tongue -- as weight is loaded forward and aft of the trailer axle.

Each gallon of water you carry in the fresh water tank, aft of the axle, not only adds 8.34 pounds to your Gross Trailer Weight (GTW), it also lifts weight from the trailer tongue at the same time. You can choose the amount of water to carry in the fresh water tank while on the road, but the water heater is always full of water. The 6 gallon water heater, aft of the axle, holds 50 lbs of water. Adding propane tanks full of gas adds to the GTW and tongue weight. Each empty propane tank weighs just under 17 lbs; fill the tank with propane and it’s weight is about 37 lbs. Tongue weight is reduced as you consume propane during your camping trip. Clothes, pots and pans, food and camping gear also all add to the GTW and will change your tongue weight depending on how far aft or forward of the axle they are packed into the trailer. Add every pound of water, propane, clothes and gear to the fully configured base weight of of your Casita.

It’s surprisingly easy to load up to 700, or more, pounds of weight to your trailer, packing it for camping trips, especially for trips of a week and more.

The dry base model factory weight of our 17’ Freedom Deluxe (FD) is listed at 2,480 lbs. The furnace, microwave, and awning factory add-on options increases the base dry weight of our FD.  Clothes, food, gear, water, and propane adds more weight.  

Fully loaded for travel, with just 6 gallons of water in the fresh tank, our FD GTW for our last month long road trip was 3,233 lbs, with 363 lbs (11.2%) of that weight resting on our tow vehicle hitch. 

Note: Our 17’ FD is loaded with every available factory option, including furnace, awning, and microwave, plus some custom add-ons. Our Casita also has the weight of a receiver hitch and StowAway box on the back plus a propane tank cover topped with an ATV box on the front tongue. Added altogether, our actual “dry” GTW starts much higher than the 2,480 pound base FD model weight. 

There are multiple approaches to track the total Gross Trailer Weight of your trailer, and how much of that weight is distributed between the axle and tongue. All the approaches include a stop at the scale to get those 3 weights. I go to local truck stops to use their ”Cat Scale“ Certified Public Scale station to weigh our tow vehicle and Casita rig.
http://www.publicscaleslocator.com 
https://catscale.com/how-to-weigh/
While at the scale, you’ll first pull your full rig onto the three scale pads — Casita axle on one pad, tow vehicle rear axle on the next pad, and tow vehicle front tires on the front pad. Get the weigh ticket with those three weights. Then pull your rig around to a parking area and unhitch your Casita. Reweigh your tow vehicle using two scale pads — tow vehicle rear axle on one pad and tow vehicle front tires on the next pad. Get the weigh ticket with those two weights. Then calculate the Casita’s tongue / hitch weight: This is the difference between the two tow vehicle rear axle weights — with and without the casita hitched. Calculate the gross weight of the Casita itself: This is the Casita axle weight from the combined rig weighing plus the calculated tongue / hitch weight. Calculate the percentage of the camper’s tongue weight: This is the tongue / hitch weight divided by the camper’s gross weight.

My approach — I weighed our trailer with empty fresh, gray, and black water tanks, full hot water and propane tanks, and our standard camping gear always stowed in the trailer, including our StowAway box on the back of our Casita. That gave me our 3 base trailer weights. I have a packing checklist spreadsheet with the weight of everything we pack for trips and I calculate our loaded for travel GTW. Our loaded for travel tongue weight is to 11-12% of GTW. The first couple of times we loaded our newest camper - a 17’ FD - for travel, I used our bathroom scale to check the tongue weight. Or you can load your trailer for travel and stop at a public scale to get your weights. Follow the links I gave in an earlier reply for the the how-to get your three weights at public scales.

More:

1 comment:

  1. Do you think that my Highlander Hybrid that has a max towing capacity of 3500 lbs and a max tongue weight of 350 could handle the 17' Casita?

    ReplyDelete

Helpful Links

Casita Life is available to all who love the small camper lifestyle. We believe the best camping information and advice comes from the peo...